Hair roller containing temperature indicator

ABSTRACT

A temperature indicator which consists of a suspension of a cuprous mercuric iodide complex in a transparent carrier, which is able to protect the complex indicator compound against deterioration from sublimation of the mercuric part of the complex and to protect the same against the detrimental influence from the ambient atmosphere such as oxygen. The indicator may be further protected by a transparent cured cover, and it will change its color at 65*-75* C from red to black, when heated and back again to red when cooled. These temperature indicators are particularly adopted for use on heated hair rollers to identify to the user, when each roller is ready for use.

- :r 1 1 1. Unted States tet 1 3,665,938 Pedersen 51 30, I972 [54] HAIRROLLER CONTAINING 1,693,369 11/1928 Cochran ..252/408 x TEMPERATUREINDICATOR 2,892,798 6/1959 Dobbs ..252/408 3,078,182 2/1963 Crone....252/408 X [72] 1mm: fi f f g g fi I'm/"elem 3,352,794 11/1967 Abdo..252/408 [73] Assignee: Bristol Myers Company, New York, N.Y. PrimaryExaminer-Robert F. Burnett Assistant Examiner-M. E. McCamish [22] 1970Attorney-Waters, Roditi, Schwartz & Nissen [21] Appl. No.: 6,332

[57] ABSTRACT Related U.S. Application Data I A temperature indicatorwhich consists of a suspenslon of a commuanon'm'pan of 612,102, Jamcuprous mercuric iodide complex in a transparent carrier, 1967'abandoned which is able to protect the complex indicator compoundagainst deterioration from sublimation of the mercuric part of [52] U.S.Cl. ..132/33 R, 34/96, 132/39 R, the complex and to protect the Sameagainst the detrimental 5 l I Cl 252/408 influence from the ambientatmosphere such as oxygen. The d 34 agg f g indicator may be furtherprotected by a transparent cured 1 le 0 are i cover, and it will changeits color at 65-75 C from red to black, when heated and back again tored when cooled. These temperature indicators are particularly adoptedfor use on [56] References cued heated hair rollers to identify to theuser, when each roller is UNITED STATES PATENTS ready for 3,25 7,5416/1966 Jorgensen 132/33 R 9 Claims, No Drawings HAIR ROLLER CONTAININGTEMPERATURE INDICATOR CROSS-RELATED APPLICATION This application is aC-I-P of my earlier application Ser. No. 612,102 filed Jan. 27, 1967 andnow abandoned.

BRIEF SUMMARY OF THE INVENTION The present invention relates to atemperature indicator consisting of a cuprous mercuric iodide complexincorporated in a transparent carrier. When heated to a temperaturewhich is characteristic for the complex, the indicator changes color,and the indicator reverts to the starting color when cooled below thecharacteristic temperature.

Temperature indicators similar to the aforesaid are known.

By way of example, US. Pat. No. 1,693,369 describes a mixture of cuprousiodide and mercuric iodide incorporated in transparent carriers such asvarnishes, resins or plastic materials. The color changing pigment is amixture and the mercuric iodide part, which represents about 70 per centof the mixture will easily precipitate, when suspended in thetransparent varnish, due to the higher density, leaving the noncolorchanging cuprous iodide as a top layer thus making the indicatornon-operable. Furthermore the mercuric iodide part of the mixture willtend to sublimate from the top layer when heated, whereby thetemperature indicator will have very short durability. Finally, oxygenmay penetrate the varnish and in combination with the heat, oxidize thecuprous iodide to form a dark composition, which is then unable tochange color.

U.S. Pat. No. 3,352,794 describes a reversible temperature indicatorincorporated in a resin or varnish. The color changing pigment of theindicator consists of an impure iodide of silver and mercury and theindicator is operative between 27 and 218 C during which the pigmentgradually changes color from yellow to orange to red to maroon to purpleand to black. This indicator is not able to give a Sharp change in colorat a particular temperature at which preheated hair rollers are usable.

Temperature indicators, where the color changing pigments are dispersedin transparent carriers such as resins or varnishes are also disclosedin US. Pat. No. 3,386,807, which describes the use of a copolymer ofpolyvinyl chloride and polyvinyl acetate as a transparent carrier. Thiscarrier has permeability to steamin order to usable in connection withthe indicator pigment which is employed. Such permeability, however, isabsolutely intolerable with the indicator according to the invention.

U.S. Pat. No. 3,078,182 describes the use of a copolymer of vinylidenechloride as a carrier for irreversible temperature indicators, which areable to give separate indication as to whether the indicator has beensubjected to dry heat, moist heat or actinic radiation. Thus the carrieris permeable to steam.

The known reversible color changing temperature indicators thus sufferfrom drawbacks which make then unsuitable for use in connection withheated hair rollers.

An object of this invention is to provide a temperature indicator whichis adaptable for use with hair rollers at the ordinary operatingtemperatures thereof and which overcomes the known drawbacks. Theindicator has the following characteristics:

1. it is reversible in color at a particular temperature.

2. It distinctly changes color from red to maroon/black when heated to atemperature between 65 to 75 C, and instantly shows reverse color changewhen cooled below this temperature.

3. the tolerance of the color change is less than 1 2 C.

4. the indicator is continuously operable for more than 1,000 hours,which represents more than years of regular use of heated hair rollers.

5. the color changing pigment is a chemical complex compound which willdisintegrate by precipitation as the mixed pigments of the knownindicators when suspended in a carrier.

According to the invention the color changing pigments have the formulax Cul, y Hgl, where x and y refer to the same or difierent integersbetween 1 and 6. These complexes are synthesized in known manner frompotassium iodide, cupric sulfate and mercuric chloride and the like. Ina particular embodiment, y is l andx is l or 2.

The single dried complex is ball-milled and sifted, and then mixed withthe transparent carrier.

The transparent carrier consists of a varnish or a lacquer which in drycondition has very little permeability to sublimizing mercuric iodideand to oxygen. For example there may be employed a copolymer ofmonochlorotrifluoroethylene and vinylidene fluoride, known as Kel-F, orpolyvinylacetate. The two carriers are not limiting with respect to thescope of the invention are are only offered by way of example.

Suitable solvents for the carriers are methylethylketone, toluene orethylacetate.

The mixture of color changing pigment and transparent carrier is paintedon the objects where the surface temperature is to be checked, e.g., atthe top or side of a heat retaining hair roller. After drying, theindicator is ready for use.

It is to be understood that the temperature indicator can be applied tothe hair roller in other ways within the scope of the invention. Thusthe indicator may be placed on a foil, which is then transferred to theobject, or the object can be inscribed with a printing ink made from thechemical complex.

To protect the temperature indicator from mechanical damage and therebyto prolong the life of the indicator, it is sealed within a transparentcover, which may be applied as a curable layer consisting, for example,of unsaturated polyester or applied as a foil consisting, for example,of a polyolefin or a saturated polyester.

As a result, the obtained temperature indicator is specially suited forobjects, which are used frequently, e.g., at least twice a week, and theindicator will retain its temperature indicating property without changefor many years.

DETAILED DESCRIPTION The following examples set forth embodiments ofthis invention, but are in no way limiting.

EXAMPLE I 1.0 g of Kel-F resin is dissolved in 1.0 g methylethylketoneand to the resulting solution is added 1.0 g cuprous mercuric triiodide(CuHgl After stirring, a paint is obtained which is applied dropwise insmall bores at the top of a hair roller. When the solvent has evaporatedfrom the paint, each indicator dot is covered with a layer of anunsaturated polyester, which is pre-mixed with l per cent peroxidehardener e.g. cyclohexanone peroxide and 0.01 per cent of a cobaltaccelerator, e.g. cobalt octoate. When the cover has hardened, theindicator is ready for use and tests made on hair rollers show theindicators completely faultless after storage at C for 1,000 hours.

EXAMPLE II 4.2 g of polyvinvlacetate are dissolved in 2.8 g ofethylacetate and 6.0 g of toluene. To the solution are added 7.0 g ofcuprous mercuric tetraiodide (Cu I-IgI and the solution is stirred toform a paint. A 0.1 mm. thick polyester foil is coated with theresulting stirred paint and dried. Suitable size pieces are stamped outfrom the coated foil and placed on hair rollers made from polypropylene.Corresponding shaped pieces are stamped from a 0.1 mm. thickpolypropylene foil and placed over the indicator dots. This cover isthen welded in known manner to the polypropylene surface of the hairroller, thus sealing the indicator dot from physical damage. Tests showthe indicator to be completely faultless after storage at 100 C for1,000 hours.

The invention is useful when it is necessary to indicate if a varyingsurface temperature is above or below 65 to 75 C. The temperatureindicator according to the invention can particularly be used on hairrollers, which prior to their use are heated to a surface temperature ofabout 75 C, which is necessary to give an efiective curling within -15minutes, determined by the themial capacity of the hair roller.

Particular embodiments of the invention have been used to illustrate thesame. The invention, however, is not limited to these embodiments. Inview of the foregoing disclosure, variations or modifications thereofwill become apparent to those skilled in the art within the scope of theinvention as defined by the appended claims.

What is claimed is:

l. A heatable hair roller having a temperature indicator for visuallyindicating a predetermined temperature for the hair roller during use,said indicator consisting essentially of a chemical compositionsuspended in a transparent carrier, said indicator having reversiblecolor change at the predetermined temperature, said composition being aninorganic chemical complex compound consisting of cuprous mercuriciodide having the formula x Cul, y Hgl wherein x and y are the same ordifferent integers between 1 and 6; a transparent cured film of plastic,said indicator being placed on said hair roller and being covered by andsealed from the ambient atmosphere by said transparent cured film ofplastic.

2. A hair roller as claimed in claim 1 wherein said transparent curedfilm of plastic consists of a polyester or a polyolefin.

3. A hair roller as claimed in claim 1 wherein y is l and x is l or 2.

4. A hair roller as claimed in claim 1 wherein said complex has a colorchange at a temperature between 65 and 75 C.

5. A hair roller as claimed in claim 4 wherein said carrier isconstituted of a material which is substantially impermeable to oxygenand to sublimizing mercuric iodide from said complex.

6. A hair roller as claimed in claim 1 wherein the hair roller includesa roller member constituted of polypropylene and said film ispolypropylene and is welded to said roller member with the indicatorinterposed therebetween.

7. A hair roller as claimed in claim 1 wherein the hair roller includesa roller member and the indicator is painted on said roller member.

8. A hair roller as claimed in claim 1 wherein the hair roller includesa roller member and the indicator is mounted on a foil applied to theroller member.

9. A hair roller as claimed in claim 1 wherein the hair roller includesa roller member and said film is a polyester joined to said rollermember with the indicator interposed therebetween.

2. A hair roller as claimed in claim 1 wherein said transparent cured film of plastic consists of a polyester or a polyolefin.
 3. A hair roller as claimed in claim 1 wherein y is 1 and x is 1 or
 2. 4. A hair roller as claimed in claim 1 wherein said complex has a color change at a temperature between 65* and 75* C.
 5. A hair roller as claimed in claim 4 wherein said carrier is constituted of a material which is substantially impermeable to oxygen and to sublimizing mercuric iodide from said complex.
 6. A hair roller as claimed in claim 1 wherein the hair roller includes a roller member constituted of polypropylene and said film is polypropylene and is welded to said roller member with the indicator interposed therebetween.
 7. A hair roller as claimed in claim 1 wherein the hair roller includes a roller member and the indicator is painted on said roller member.
 8. A hair roller as claimed in claim 1 wherein the hair roller includes a roller member and the indicator is mounted on a foil applied to the roller member.
 9. A hair roller as claimed in claim 1 wherein the hair roller includes a roller member and said film is a polyestEr joined to said roller member with the indicator interposed therebetween. 